/Engine/Plugins/FX/Niagara/Source/Niagara/Classes/NiagaraSystem.h
Looks at all the event handlers in the emitter to determine which other emitters it depends on.
void FindEventDependencies ( [FVersionedNiagaraEmitterData](API\Plugins\Niagara\FVersionedNiagaraEmitterData) * EmitterData, [TArray](API\Runtime\Core\Containers\TArray)< [FVersionedNiagaraEmitter](API\Plugins\Niagara\FVersionedNiagaraEmitter) > & Dependencies )